A man who died after he was attacked at a Christmas Day party in Rochdale was stabbed in the back, police have said.

John Lee Barrett, 31, from Harpurhey, Manchester, was knifed during a private function at Sinclair's Bar, a nightclub.

It is believed he had been hit over the head with a glass or bottle immediately before the stabbing, police said.

Greater Manchester Police were called to the venue, on Drake Street, at about 2.40am on Sunday following reports of a large disturbance.

The club's security staff had already thrown out a number of people who were inside and police officers closed the premises.

Mr Barrett was found with stab wounds and taken to hospital where he died on Tuesday, GMP said.

A post mortem examination concluded he died from a stab wound to the back.

Chief Superintendent John O'Hare, said: "This will be a lengthy and complicated investigation due to the number of people in the club at the time of the incident. We have spoken to a number of witnesses, but we are still extremely keen to hear from anyone who was there that night.

"If you were at Sinclair's Bar in the early hours of Christmas Day and we haven't yet spoken to you then please get in touch - your information could be vital."

Anyone who has information should call police the Major Incident Team on 0161 856 3691, police on 101, or the independent charity Crimestoppers, anonymously, on 0800 555 111.